Dimethyl-cyclohexanecarboxylic acid esters in perfumery

ABSTRACT

The invention concerns perfumes containing as fragrance materials 1,4-dimethyl-cyclohexane-1-carboxylic acid esters of general formula wherein R is an alk(en)yl group having 1-4 carbon atoms, preferably R$(1,3)methyl. The fragrance materials have very agreable fresh herbal ordours with green and floral notes.

This is a 371 of PCT/EP93/03548 filed Dec. 9, 1993.

The present invention relates to the use of certaindimethyl-cyclohexanecarboxylic acid esters as fragrance materials and toperfumes and perfumed products containing these compounds.

Many synthetic perfume components have been developed, especially in thelast decades to substitute known perfume materials of natural origin.Nevertheless there is a constant need for new synthetic perfumecomponents which are more stable than those previously developed and/orhave additional or more delicate odour notes to further complete thefragrance palette from which the perfumer can chose in composingperfumes which are suitable also for various agressive environments.

Various substituted cyclohexene- and cyclohexadienecarboxylic acidesters are known as fragrance materials in the art of perfumery. Themajority of them are of the 2,6,6-trimethyl- or the2-ethyl-6,6-dimethyl-substituted type and were developed in analogy tovarious compounds found in nature possessing the2,6,6-trimethylcyclohexene moiety. Such compounds, with the double bondin the 1- or 2-position and sometimes containing an additional methylgroup in the 3-position are described e.g. in EP-A-0 056 109, GB 1 497498 and U.S. Pat. No. 4,375,001 and various other patents and patentapplications mentioned therein. In EP-A-0 053 704 corresponding2,3,6,6-tetramethyl- and 2-ethyl-6,6-dimethyl-cyclohexane-1-carboxylicacid esters are described. Thus, these compounds are all heavilysubstituted with methyl and ethyl groups. The odors reported may varyconsiderably although in many cases fruity and floral, especiallyroselike dours are reported.

In EP-A-0 199 330 1,4,6-trimethylcyclohex-3-ene derivatives, includingmethyl 1,4,6-trimethylcyclohex-3-ene-1-carboxylate, are reported to beof use in perfumery. They appear to have mostly herbal woody, evenpatchouli-like, odors and thus appear to be distincty different in odourcharacter from the 2,6,6- and 2,3,6,6-substituted cyclohexenecarboxylicacid esters reported above. In EP-A-0 199 330 this is attributed to thepresence of the quaternary carbon atom in the 1-position. Nevertheless,methyl 1-methylcyclohex-3-ene-1-carboxylate, which is marketed as afragrance material, has a predominantly fruity odour, which seems to bein contradiction with this rule.

Ethyl 2,4-dimethyl-cyclohexane-1- carboxylate, on the other hand, isalso marketed as a fragrance material, but with a distinctly floralodour.

Methyl and butyl 1,4-dimethylcyclohex-3-ene-1-carboxylate stereoisomershave been descibed in CH-A-680 853. The (-)-S methylester is describedto have a rather uninteresting herbal, humus and woody and also slightlychemical type of odour whereas the (+)-R isomer has an agreeable freshfruity-menthol-anis-like odour. The racemic mixture is describes asbeing spoiled from a perfumery point of view by the odour contributionof the (-)-S isomer.

Finally, in U.S. Pat. No. 4,392,976 4-methyl-cyclohex-3-ene-1-carboxylicacid is reported to have a cumin-like odour. No mention is made of anyesters of this acid.

It has now been found that 1,4-dimethylcyclohexane-1-carboxylic acidesters of the general formula: ##STR1## wherein R is an alk(en)yl grouphaving 1-4 carbon atoms, are valuable fragrance materials having veryagreeable fresh herbal odours with green and floral notes. The methylesters are especially preferred. Although the methyl esters are known assuch, e.g. from H. van Bekkum et al, Recl. Tray. Chim. Pays-Bas, 88(3)301-6, 1969 and from W. G. Schindel, R. E. Pincock, J. Org. Chem.,35960, 1789-94, 1970, no mention is made of any organoleptic property.

The compounds may be prepared by methods known in the art, particularlyby Diels-Alder reaction of the corresponding methacrylate ester withisoprene, followed by hydrogenation and separation of the 1,3-dimethylfrom the 1,4-dimethyl esters. A mixture of cis-dimethyl andtrans-dimethyl esters is thus obtained which may be separated into itscomponents by methods described in the art, e.g. by W. G. Schindel, videsupra. Also the racemic micture obtained may be separated according tomethods known in the art e.g. as decribed in CH-A-680 853 above.However, contrary to what is desribed therein, for the use of thecompounds of this invention as fragrance material such separations aresuperfluous.

The esters according to the invention may be used as such to givevarious odour notes of the floral, green and fruity type to all sort ofproducts, or they may be incorporated in perfumes. For the purposes ofthis invention a perfume is defined as a mixture of various fragrancematerials, if desired dissolved in a suitable solvent or mixed with asolid substrate, which is used to provide a desired odour to the skin orto all sorts of products. Examples of such perfumed products are: fabricwashing powders and liquids and other fabric care products; detergentsand household cleaning, scouring and disinfection products; airfresheners, room sprays and pomanders; candles; soaps, shampoos andother personal cleaning products; cosmetics such as creams, ointments,toilet waters, preshave-, aftershave- and other lotions, talcum powders,body deodorants and antiperspirants.

Known fragrance materials which may be advantageously combined with theesters according to the invention may be natural products such asextracts, essential oils, absolutes, resinoids, resins, concretes etc.,but also synthetic materials such as hydrocarbons, alcohols, aldehydes,ketones, ethers, acids, esters, acetals, ketals, nitriles, etc.,including saturated and unsaturated compounds, aliphatic, carbocyclicand heterocyclic compounds. Such fragrance materials are mentioned, forexample, in S. Arctander, Perfume and Flavor Chemicals (Montclair, N.J.,1969), in S. Arctander, Perfume and Flavor Materials of Natural Origin(Elizabeth, N.J., 1960) and in "Flavor and Fragrance Materials--1991",Allured Publishing Co. Wheaton, Ill. USA.

Examples of fragrance materials which can be used in combination withthe esters according to the invention are: geraniol, geranyl acetate,linalol, linalyl acetate, tetrahydrolinalol, citronellol, citronellylacetate, dihydromyrcenol, dihydromyrcenyl acetate, tetrahydro-myrcenol,terpineol, terpinyl acetate, nopol, nopyl acetate, 2-phenylethanol,2-phenylethyl acetate, benzyl alcohol, benzyl acetate, benzylsalicylate, styrallyl acetate, benzyl benzoate, amyl salicylate,dimethylbenzyl carbinol, trichloromethylphenylcarbinyl acetate,p-tert-butyl cyclohexyl acetate, isononyl acetate, vetiveryl acetate,vetiverol, α-hexylcinnamaldehyde,2-methyl-3-(p-tert-butylphenyl)propanal,2-methyl-3-(p-isopropylphenyl)propanal, 3-(p-tert-butylphenyl)-propanal,tricyclodecenyl acetate, tricyclodecenyl propionate,4-(4-hydroxy-4-methyl-pentyl)-3-cyclohexenecarbaldehyde,4-(4-methyl-3-pentenyl)-3-cyclohexenecarbaldehyde,4-acetoxy-3-pentyltetrahydropyran, 3-carboxymethyl-2-pentylcyclopentane,2-n-heptylcyclopentanone, 3-methyl-2-pentyl-2-cyclopentenone, n-decanal,n-dodecanal, 9-decenol-1, phenoxyethyl isobutyrate, phenyl-acetaldehydedimethylacetal, phenylacetaldehyde diethylacetal, geranyl nitrile,citronellyl nitrile, cedryl acetate, 3-isocamphylcyclohexanol, cedrylmethyl ether, isolongifolanone, aubepine nitrile, aubepine, heliotropin,coumarin, eugenol, vanillin, diphenyl oxide, hydroxycitronellal,ionones, methylionones, isomethylionones, irones, cis-3-hexenol andesters thereof, indan musks tetralin musks isochroman musks macrocyclicketones, macrolactone musks ethylene brassylate, aromatic nitromusks.

Solvents which can be used in perfume compositions which containcompounds according to the invention are, for example: ethanol,isopropanol, diethylene glycol monoethyl ether, dipropylene glycol,diethyl phthalate, triethyl citrate, etc.

The quantities in which the esters according to the invention can beused in perfumes or in products to be perfumed may vary within widelimits and depend, inter alia, on the nature of the product, on thenature and the quantity of the other components of the perfume in whichthe compounds are used and on the olfactive effect desired. It istherefore only possible to specify wide limits, which, however, providesufficient information for the specialist in the art to be able to usethe esters according to the invention for his specific purpose. Inperfumes an amount of 0.01% by weight or more of the esters according tothe invention will generally have a clearly perceptible olfactiveeffect. Preferably the amount is 0.1% by weight and may be up to 80% byweight. The amount of esters according to the invention present inproducts will generally be at least 0.5 ppm by weight.

The following examples are only intended to illustrate the preparationand use of the esters according to the invention, but the invention isnot in any way limited thereto

EXAMPLE 1 Synthesis of methyl 1,4-dimethylcyclohexane-1-carboxylates

A mixture of methyl methacrylate (135 g; 1.4 mol) and isoprene (137 g;2.0 mol) in a pressurized reaction vessel was quickly heated to 250° C.,kept at that temperature for 100 minutes and quickly cooled to roomtemperature. The crude reaction mixture obtained (270 g) comprised 75%of the cyclohexene-carboxylates and only minor amounts of startingmaterials.

This mixture was hydrogenated at 100° C. and atmospheric pressure usingabout 200 mg 5% palladium on carbon as a catalyst. Thedimethyl-cyclohexane-carboxylates in the crude reaction mixture afterhydrogenation consisted of 23% 1,3-dimethyl- and 77% 1,4-dimethylisomers. This mixture was carefully fractionated under reduced pressureyielding 94 g (35%) of perfumery grade product (Bpt. 85°-87° C. at 2kPa). This product consisted of 17% 1,3-dimethyl isomers, 51.5%trans-1,4-dimethyl isomer and 31.5% cis-1,4-dimethyl isomer.

EXAMPLE 2

A herbaceous floral perfume for use in household products at 0.2% wasprepared according to the following recipe.

    ______________________________________                                        Iso bornyl acetate       40.0                                                 Iso-longifolanone (Q)    11.0                                                 Dihydromyrcenol (Q)      7.0                                                  Jasmacyclene (Q)         6.0                                                  Linalyl acetate          6.0                                                  Acetyl cedrene (Q)       5.0                                                  Benzyl acetate           4.0                                                  Geranyl acetate          4.0                                                  β-Phenoxyethyl isobutyrate (Q)                                                                    4.0                                                  Linalool                 3.5                                                  Camphor powder           3.0                                                  Patchouli acid washed (Q)                                                                              2.0                                                  Dipropylene glycol       1.5                                                  Olibanum oil             1.0                                                  Methyl 1,4-dimethylcyclo-hexane-1-carboxylate                                                          2.0                                                  Total:                   100                                                  ______________________________________                                    

The addition of Methyl 1,4-dimethylcyclo-hexane-1-carboxylate makes theodour of the perfume much more sophisticated by adding a more roundedherbal character.

We claim:
 1. Perfume comprising at least 0.01% by weight of at least one1, 4-dimethylcyclohexane-1-carboxylic acid ester according to thegeneral formula: ##STR2## wherein R is an alk(en)yl group having 1-4carbon atoms.
 2. Perfume according to claim 1 wherein R is a methylgroup.
 3. Perfume according to claims 1 or 2 wherein the amount of1,4-dimethylcyclohexane-1-carboxylic acid ester is at least 0.1% byweight.
 4. Perfume products comprising at least 0.5 ppm by weight of atleast one 1,4-dimethylcyclohexane-1-carboxylic acid ester according tothe general formula: ##STR3## wherein R is an alk(en)yl group having 1-4carbon atoms.
 5. Perfumed products according to claim 4 wherein R is amethyl group.
 6. In a process for preparing perfumed products, theimprovement for enhancing odor of the product which comprises adding tothe product at least 0.5 ppm by weight at least one 1,4-dimethylcyclohexane-1-carboxylic acid ester according to the generalformula: ##STR4## wherein R is an alk(en)yl group having 1-4 carbonatoms to provide the product with a fresh herbal green odor note. 7.Process according to claim 6 wherein R is a methyl group.
 8. A processfor obtaining a perfumed effect which comprises applying to an arearequiring said effect, an effective amount of a compound according toclaim 1.